Family members of a person with special educational needs may need assistance and should be customers of professional services and interventions. Although mothers are the child primary caregiver in touch with early intervention programs, studies have increasingly shown the importance of fathers and their participation. This study aimed to evaluate whether an intervention directed at fathers changes their patterns of dyadic interactions with their baby with Down syndrome in play situations. It was used the Protocol of Analysis Categories of Interaction Footages in the analysis of five interaction shots: two before, one during, one after the intervention and a follow-up one. The father attended the behaviors training to the baby's development, with guidance on how to stimulate the child. There was an increase in the frequency of positive behaviors after the feedback given to parents and during the intervention by the end of this, indicating a positive effect of the guidelines provided. Mothers, who have not undergone the training, did not have the same gains. However, the effects on fathers were not sustained at follow-up. Children have also started to exhibit more positive behaviors in interaction. It is concluded that the objectives were achieved and it is possible to involve the father in early intervention programs aimed at better development of babies with developmental delay.